Why pinning by surface irregularities can explain the peak effect in transport properties and neutron diffraction results in NbSe2 and Bi-2212 crystals?

The existence of a peak effect in transport properties (a maximum of the critical current as function of magnetic field) is a well-known but still intriguing feature of type II superconductors such as NbSe2 and Bi-2212. Using a model of pinning by surface irregularities in anisotropic superconductors, we have developed a calculation of the critical current which allows estimating quantitatively the critical current in both the high critical current phase and in the low critical current phase. The only adjustable parameter of this model is the angle of the vortices at the surface. The agreement between the measurements and the model is really very impressive. In this framework, the anomalous dynamical properties close to the peak effect is due to co-existence of two different vortex states with different critical currents. Recent neutron diffraction data in NbSe2 crystals in presence of transport current support this point of view

Vulcanodinium rugosum - a potent and ubiquitous genus affecting mice and man [résumé]

Dinophyte Seminars, en ligne, , 08-/06/2022 -The monotypic genus Vulcanodinium was erected in 2011 [1], and the unique species V. rugosum was associated with the production of pinnatoxins the same year [2]. According to its morphology, V. rugosum is closely related to peridinioid/scrippsielloid dinoflagellates, such as the genus Bysmatrum from which it can be distinguished mainly by the pattern of anterior intercalary plates. Based on LSU rDNA sequence data, the taxon was shown to belong to the order Peridiniales but it was not possible to affiliate it to a particular family, and molecular data showing a rather high divergence from other peridinioids supports the erection of the genus. Few studies focused on the life cycle of this organism [3, 4], but while V. rugosum has been observed as a pelagic species, it also frequently forms clusters of non-motile (temporary cyst-like) cells embedded in a highly adherent mucous. Its pelagic life forms obviously may contribute to its spread and some of the effects discussed below. Pinnatoxins (PnTXs), and their derivatives, pteriatoxins (PtTXs), are a group of macrocycles with cyclic imine and spiro-functions similar to spirolides and have been identified in shellfish well before the discovery of their causative organism [5-9]. Pinnatoxins are potent neurotoxins that were discovered using an isolation scheme bioguided by intraperitoneal mouse bioassay [7]. The toxins act via blocking neurotransmission through their strong binding to the nicotinic acetylcholine receptor [10, 11], and also activate Ca2+-channels and inhibit expression of vascular cell adhesion molecule 1 (VCAM-1) [12]. After isolation of a peridinioid dinoflagellate producer in New Zealand and the isolation of pinnatoxins E and F in 2010 [13, 14], pinnatoxins were also rapidly reported in Australia, China, Japan, Canada and Europe in both algal strains and shellfish in areas of different ecology, notably Norway and France [2, 4,15-20], even if numerous ecological studies suggest warm water temperatures as a driver for significant bloom development [21-24]. There is significant diversity of PnTXs among strains isolated from different regions which may vouch for further studies on intra-specific genetic diversity, and ballast water or other ship vectors have been suggested as a possible route of distribution of these organisms around the globe. Studies on the cytotoxicity of the first French strain suggested presence of several toxins [25, 26]. Indeed, a novel toxin, i.e. portimine, was simultaneously reported from a New Zealand strain. Portimine is a small macrocycle that also contains a cyclic imine group but only a single carbon with spiro-functionality, and presents greater cytotoxicity than PnTXs. Contrarily to the diversity of PnTXs, all strains characterized globally appear to produce portimine. Shellfish appear to preferentially accumulate PnTXs rather than portimine, and PnTXs have been classified as fast acting or presenting atypical toxicity observed in mice, i.e. symptoms within 15 min. Still, to date, no acute intoxication through consumption of shellfish by humans has been confirmed to have been caused by PnTXs. Surprisingly, a bloom of V. rugosum in Cienfuegos Bay, Cuba, has been reported to cause dermatitis in bathers [24], and we report here an event in Senegal where, in addition to PnTX-H, record values for portimine occurred in an offshore environment affecting artisanal fishermen with similar symptoms in 2020 and 2021. Further research is underway to elucidate causative compounds and mechanisms of toxicity as well the genetic signature of strains involved

A comparative profitability analysis of transcatheter versus surgical aortic valve replacement in a high-volume French hospital

Abstract Background Current scientific guidelines have extended the indication for transcatheter aortic valve replacement (TAVR) to patients who present an intermediate risk for surgery and have been so far considered for conventional surgery. We previously demonstrated that the TAVR procedure generated profits despite elevated costs, but comparison with surgery has not been performed. The objective of this study was to assess the profitability of the TAVR procedure compared with conventional surgery in a high-volume French hospital. Consecutive patients eligible for transfemoral TAVR or surgical aortic valve replacement (SAVR) were included retrospectively in this single-centre study between September 2014 and December 2015. The primary endpoint was the profitability of each procedure (defined as the ratio between the profit and total revenues), calculated for each patient. Secondary composite endpoints included major adverse events in the 30 days following procedure and breakdown of costs. Results Two hundred and thirty-eight patients were included in the TAVR group and 341 in the SAVR group. TAVR patients presented higher operative risk scores and more comorbidities. Compared with SAVR, TAVR was associated with higher profits (€2732 ± 1768 per patient vs. €2177 ± 2437 per patient, P < 0.001) but also higher costs (€27,778 ± 4961 vs. €17,813 ± 6071, P < 0.001) resulting in lower profitability (9.3 ± 5.7% vs. 11.7 ± 10.1%, P < 0.001). The price of the bioprosthesis represented 70% of the TAVR total cost. Conclusions TAVR performed in carefully selected patients was associated with higher profits than SAVR, but also higher costs resulting in lower profitability